As soon as her attention was occupied Carter moved at once to the end of the shelf that Miss Strong had indicated and removed the fifth book. To his amazement he found nothing whatever concealed between the leaves. The books on either side on the same shelf failed to yield up anything. He tried the shelf above and the shelf below. Perhaps Miss Strong had been mistaken in the directions. He examined the books at the other end. There was nothing there. He recalled that the girl had said that no one except two girls had entered the store between the time she had discovered and copied the cipher and the time of his arrival. If these girls had not taken the message away there could be only one other explanation—the clerk in the bookstore must have removed it and concealed it somewhere. “Which of the war books do you think the best?” he asked for the purpose of starting a conversation. “There’s that many it is hard to say, sir,” the young woman answered. Something in her inflection made him look sharply at her. Her accent surely was English, or possibly Canadian. A few judicious questions quickly brought out the information that she came from Liverpool and that she had three brothers in the British army. Carter decided that it was preposterous to suspect her of being in league with German agents. There was only one other thing that could have happened. Some one else—some one who had eluded Miss Strong’s notice—had removed the cipher message. Promptly he had telephoned to her to meet him. He was glad that he had done so, for her evident perturbation as she answered the ’phone both interested and puzzled him. Pausing just long enough to report to Chief Fleck, he hastened to the rendezvous, arriving there first. He selected a bench apart from the others, where the wall jutted out from the walk, and seating himself, idled there as if merely watching the river. In obedience with his instructions Jane, when she arrived, planted herself nonchalantly on the same bench, and paying no attention to him, pretended to be reading a letter. Presently Carter rose and stretching himself lazily, as if about to leave, turned to face the Drive, his keen eyes taking in all the passers-by. Apparently satisfied, he sat down abruptly and turned to speak to the girl beside him. “All right, K-19,” he said, “it’s safe. Now we can talk.” “I’ve got such a lot to tell,” cried Jane. “First,” said Carter, “just where did you put that cipher message when you put it back?” “What!” cried the girl, her face blanching, “wasn’t it there? Didn’t you find it?” Carter shook his head. “It must be there,” she insisted. “Are you sure you looked in the right book—the fifth book from the end on the second shelf on the up-town side of the store.” “It’s not there. I examined every book there, on the shelves above and below and at the other end, too.” “The clerk in the store, that girl—must have hidden it,” cried Jane with conviction.